Tumanako BMS Development

My friend Philip had something of a setback in his electric race car project and has launched Tumanako, an open source electric car effort, in the hope of completing what couldn't be bought. I've been working on the BMS as I wasn't happy with any of the commercial offerings -- basically they were either too expensive or too opaque. When we're finished, the Tumanako BMS will provide valuable insight into the health of your battery. You won't one day get a red light and have no idea or information or history about what your battery was doing before something went wrong.

I'm converting Bob's assembly firmware to C. The BMS uses PIC processors and it's been about 10 years since I last played with them. A lot has changed. I've made quite a lot of progress in the last week or so, I

• modified a single pair RS485 - RS232 converter to work with a dual pair network
• made a cable to connect my programmer to the port on the BMS boards
• assembled Bob's original firmware
• wrote a new firmware in C which, so far, flashes lights in response to characters on the RS485 bus

The photo above shows one BMS slave board, capable of monitoring 5 cells, mounted on top of 5 A123 M1 cells in a test rig. The empty looking circuit board is a shunt board which holds the transistors to control the balancing current. The small circuit board with plugs at either end is the RS485 - RS232 converter. I don't have a photo of flashing lights and programming cables for you today, I'm sure if you try, you can imagine something approximating a christmas tree.